This study aims to review observational methods for assessing postural loads such as OWAS, RULA and REBA, and to compare them, based on the literature survey. The literature was searched through academic database of ScienceDirect using the key words of observational methods, OWAS, RULA and REBA. The results exhibited that of the thee methods, RULA was cited in the literature and applied to manufacturing industries the most frequently. Although it has been known that RULA is appropriate for assessing upper body postures, it has been applied to healthcare and social work activities, agriculture, forestry, fishing, construction, mining and quarrying, which require unstable lower limb postures. The countries where more number of relevant studies have been carried out were USA, India, Brazil, UK, etc. It was recommended that of the three techniques, RULA may be better for assessing postural loads, because it evaluated postural loads more highly, irrespective of industry, work type and lower limb postures, and its assessment results had higher agreement rate with experts’ assessments than those of OWAS and REBA. It is expected that the results of this study will be used as a guideline for selecting an appropriate observational method.

The study evaluated the accuracy and intra-rater reliability for OWAS (Ovako Working posture Analysing System), RULA (Rapid Upper Limb Assessment), REBA (Rapid Entire Body Assessment) to improve their evaluation accuracy and reliability. Participants (n = 163) with undergraduate degree were recruited in this study and trained for 6 hours about the ergonomic assessment methods. Ergonomic assessments were conducted using OWAS, RULA, and REBA for a representative work with dynamic posture found in manufacturing industries. The study compared action categories (overall level) and detailed evaluation scores for individual body part. Action categories of the participants significantly differed from the golden reference defined by ergonomic experts. The participants underrated or omitted scores for truck (37.4% of the participants) and legs (52.8%) in OWAS. Similarly, the participants underrated or omitted additional scores for all body parts except the hand and wrist in RULA (53.5%) and REBA (54.8%). On the other hand, the participants overrated scores for the hand and wrist in RULA (55.2%) and REBA (39.9%). The results found in this study can help of selecting focus points and parts during assessment and education to improve accuracy and reliability of the ergonomic assessment methods.